Yeah, that happened to me also when I was using v1.25f. Played some games and the rating for my XP3000+ system dropped down to 3. About 24 hours of crunching resulted in less than 1k points due to that mess...
Like GeoffS and scoser said, get the 1.25g Beta. I'm using that now for nearly a week now and don't seem to be having that problem anymore... *knocks on wooden desk*